I wonder if the fact that F1 cars are now using the idea expressed in this thread if it no longer qualifies as a unicorn?
"The second addition for 2014 is the introduction of a thermal capture device. The similarly named Motor Generator Unit - Heat (MGU-H), attached directly to the turbocharger shaft, captures exhaust heat and coverts it, like the kinetic system, into electrical energy. This capturing device has the ability to dump power straight into the system on demand or store it in the Energy Store for later use. When activated, the MGU-H gives drivers another electric power shot to the drive wheels via the dedicated generator unit. And unlike the MGU-K, the thermal recovery unit can provide unlimited supplemental power throughout the race. For 2014, Formula 1 has limited energy recovery from the MGU-K to 2 megajoules (MJ) per lap with the ability to release stored energies to a maximum of 4 MJ per lap.
Another fancy power management trick is the way in which the MGU-H thermal unit manages turbo speed. Contrary to a conventional turbocharger system where a wastegate is used to vent out excess engine pressures derived from the turbocharger, the new unit actually controls the speed of the turbocharger impeller. The ability to speed up or slow down the turbo allows teams to not only better manage wastegate pressures in the engine but to spin up the turbocharger low in the rev cycle. As boost is enabled sooner, power comes on quicker, and that power procrastination thing known as turbo-lag essentially disappears from the equation."
Turbocharging and advanced hybrid tech coming to Formula 1 for 2014